1. Field of the Invention.
The present invention relates generally to architectural renderings, and in particular, to a method, apparatus, and article of manufacture for displaying/casting a shadow on objects in a two-dimensional architectural rendering.
2. Description of the Related Art.
In the architectural, engineering, and construction (AEC) fields, three-dimensional computer aided design (CAD) drawings are often used to design blueprints, drawings, plans, etc. However, such CAD drawings may be complex, confusing, and fail to provide an end-user (e.g., a potential client) with a drawing or visualization of the “intent” of the architect or designer. Architectural renderings are designed to illustrate the “intent” of the designer or architect in two dimensions, as opposed to three-dimensional renderings having precise fidelity, accurate, hard-lined 3D geometry, lighting and shadows. Further, it is desirable to utilize shadows to provide a more real-world appearance in a two-dimensional drawing/rendering environment. However, in the prior art, shadows were geometrically accurate in a 3D environment, or merely consisted of a dark copy of a particular object that was offset to provide an “outline” type of effect. These disadvantages of the prior art may be better understood with an explanation of drawing programs and prior art techniques for casting/creating shadows.
Three dimensional (3D) drawing programs are often very complex and difficult to use. In addition, such 3D drawing programs typically show realistic/accurate, hard-lined 3D geometry, lighting and shadows. To create a shadow in such a 3D program, a 2D shape may first be drawn. However, prior to creating a shadow, the 2D shape must be converted into a 3D shape (e.g., by extruding the 2D shape). Once the 3D shape has been extruded in a 3D environment, the user can opt to cast a shadow on the 3D shape. It should be noted that throughout the process, the user is working in a 3D drawing program. Further, once the 2D shape is extruded and the 3D shape is created, the 2D shape no longer exists and the user must work with the 3D shape and all of its accompanying complexities. In an alternative prior art 3D embodiment, the user can select and move a shadow. However, the movement of the shadow is limited and the user does not have the flexibility to customize or manipulate the shadow as desired.
As described above, it is desirable to create an architectural rendering that appears hand-drawn similar to the way an artist would work. Such architectural drawings are designed to communicate the intent of the artist. Shadows in architectural renderings follow a particular convention, and are not the geometrically precise shadows that would be generated from a 3D program. Instead, such shadows are cast by flat surfaces at various distances from the camera and light sources. For example, a shadow may merely be an outline or offset darkened copy of the 2D shape.
FIG. 1 illustrates a prior art drawing with a shadow. As illustrated, the square 100 merely has an offset darkened copy 102 of the square as a shadow. Further, the corners of box 100 and shadow 102 are not connected. Accordingly the prior art fails to achieve a concept or sense of depth. To create the shadow illustrated in FIG. 1, the user may merely be presented with an option to display a shadow or the user may select the box 100 that already has the shadow 102 defined for it.
Alternatively, a user could elect to create an effect on a particular layer of a drawing while specifying various parameters for the shadow on the layer (e.g., an angle, distance, intensity, or other attributes). For example, the ShadowCaster™ product available from A Lowly Apprentice Production provides a method referred to as DropShadow™ that may be used to create a shadow. However, such a drawing program fails to allow the user a mechanism for specifying a single lighting location in a drawing that is used to cast shadows on multiple objects with differing heights. In this regard, such prior art products merely provide for shadows that are cast by a flat surface at a various distance from a camera and light source. Further, as described above, drop shadows are merely shadows that are dropped/displayed beneath an object so that the object appears to hover above the canvas. Accordingly, the shadows do not appear realistic and the corners of the object and shadow are not connected.
In view of the above, what is needed is a mechanism for casting shadows on a flat two-dimensional vector-based drawing (e.g., an architectural rendering such as an elevation view), as if the flat drawing has depth in an easy and efficient manner.